1. Field of the Invention
The present invention generally relates to semiconductor nanoparticles (“quantum dots”). More particularly, it relates to polymer films incorporating heavy metal-free quantum dots.
2. Description of the Related Art including information disclosed under 37 CFR 1.97 and 1.98.
Multi-phase and two-phase polymer films containing heavy metal-free semiconductor nanoparticles dispersed in an inner phase which is then dispersed in a suitable gas barrier outer phase have been described previously—see, e.g., U.S. Pub. No. 2015/0047765 “Quantum dot films utilizing multi-phase resin” and U.S. Pub. No. 2015/0275078 “Quantum dot compositions.”
However, there have been many challenges in obtaining truly stable films especially under testing conditions that include a dark test (0/60/RH) [0 mW/cm2 irradiance/at 60° C./RH=room humidity (not measured)] in addition to a light test (106/60/90) [90% relative humidity]. The dark test is especially challenging for currently available red-emitting quantum dots (QDs) utilized in conjunction with barrier films having a water vapor transmission rate (WVTR) on the order of 10−2 g/m2 day (e.g., i-Components TBF1004 barrier film, i-Components Co. Ltd., 701, Family Tower, 958-2, Youngtong-dong, Paldal-gu Soowon-si, Gyeonggi-do, Korea) having a resin film thickness of 50 microns or less.